Instruments



March 19, 1957 Filed Nov. 9, 1953 A. E. LE VAN 2,785,696

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Arm/ms r5 March 19, 1957 A, 5 LE VAN 2,785,696

INSTRUMENTS Filed Nov. 9,1955 4 Sheets-Sheet 2 anmmmmummlmmmlm llllllllllllllllllllllllllllllllllll gy M Mate/3&2;

Arron 26 March 19, 1957 A. E. LE VAN 2,785,696

INSTRUMENTS Filed Nov. 9, 1953 4 Sheets-Sheet 3 IIIIIIII/l/I/l/l/l INVENTOR. QMBKGSE E. /v

rates 1 2,785,696 INSTRUMENTS Application November 9, 1953, Serial No. 391,049 6 Claims. (Cl. 13785) This invention relates to instruments for controlling or indicating purposes and particularly to one involving a pneumatic operating arrangement.

A measured variable, such as temperature, pressure, flow or the like, has been employed previously to position a valve or flapper and nozzle relative to each other, the nozzle having an air supply connected thereto through a restriction. As the valve or flapper is moved to closed position relative to the nozzle by the measured variable or condition, the air pressure in the nozzle will rise and vice versa. The air pressure controlled by the flappernozzle combination can be used to operate a pressure relay or pilot which in turn can operate a controller or the output pressure can be transmitted to a remote point, the output or controlled pressure being proportional to the measured variable. The air pressure also can be used to operate an indicating or recording apparatus. A followup or feed-back means responsive to the output pressure, or to a means controlled by the instrument, can be connected to the nozzle or flapper in such a manner as to tend to return the flapper and nozzle to their original relative positions after they have been moved in response to a change in the measured variable. Previous devices have not been entirely satisfactory because of lack of sensitivity and accuracy. Also, many of the previous arrangements have been bulky, complicated, and have not been readily adaptable to varying uses.

One of the objects of this invention is to provide a universal condition responsive instrument having high sensitivity and accuracy.

Another of the objects of the invention is to provide an instrument having dynamically and statically balanced low inertia operating mechanism.

Another object of the invention is to provide an instrument arrangement which can be adjusted and tested conveniently.

In a preferred form of the device, two condition responsive means can be employed. The first can be made responsive to the measured variable, such as temperature, pressure, flow, or the like, this primary means or mechanism taking the form of a bellows, wafer, or any other type of responsive or positioning mechanism, including a bimetallic arrangement. The change in the first condition responsive mechanism preferably is fed to or used to position elements of a unitary algebraic comparing arrangement, said arrangement preferably being in the form of a unitary differential gear assembly. Preferably, the output of the condition responsive means is multiplied before it is fed to the algebraic comparing arrangement. The output motion of the differential gear assembly is connected to a flapper and nozzle combination, said output motion being the result of the change in the aforementioned condition responsive means and the feedback about to be described. The controlled pressure, nozzle or final, or means controlled thereby, can be connected to the second condition responsive means, change therein as a result of measured variable change also being fed into the algebraic comparing means, preferably through a motion multiplying mechanism. The output of the algebraic compar ing means then will be a resultant or algebraic addition of the two condition responsive devices and will be proportional to the measured variable. The output of the algebraic comparing means can be connected directly to the flapper or nozzle or through a motion changing means atent Patented Mar. 19, 1957 such as a multiplier. The algebraic comparing means preferably comprises a difierential gear mechanism arrangement described hereafter having small inertia and which is dynamically and statically balanced. The friction in the instrument will be low due to the small number of linkages and pivot points.

In a further aspect of the invention, the parts are arranged in compact form and so that the instrument can be adjusted in a simple manner from the front of the instrument. Further, the movement is easily assemblable in a compact case with a pneumatic relay or pilot. Also, a pressure testing device such as a master gauge, can be inserted through a self-sealing aperture or valve arrangement for determining the output pressure at the instrument.

These and other objects, advantages and features of the invention will become apparent from the following description and drawings, which are merely exemplary.

In the drawings:

Fig. 1 is a fragmentary perspective View with some of the parts in exploded position.

Fig. 2 is an enlarged fragmentary view partially in section taken in the direction 2-2 of Fig. 1.

Fig. 3 is a fragmentary view partially in section taken in the direction 3--3 of Fig. 2.

Fig. 4 is a fragmentary view partially in section taken along the direction 4-4 of Fig. 1.

Fig. 5 is a fragmentary enlarged sectional view taken in the direction 55 of Fig. 1.

Fig. 6 is the front view of one form of instrument assembly.

Fig. 7 is a side view of an instrument assembly including a relay or pilot, some of the parts being broken away or omitted for clarity.

The movement assembly can be attached to mounting plate 2%, the movement assembly being carried between the top or front movement plate 21 and bottom or rear movement plate 22. Condition responsive element '23 may be mounted on bracket 24, bracket 24 being carried by mounting plate 20 and being fastened thereto by means of screws 25. Condition responsive element 23 is shown in the form of a conventional set of capsules or bellows which may have its interior connected to the condition or measured variable to which the assembly is to be responsive, the measured variable being a pressure, thermostatic fluid, or other suitable operating means. In place of the diaphragm, a Bourbon tube or other types of condition responsive elements can be used such as thermostats of various kinds including expandible solids such as bimetallic elements. Condition responsive element 26 is mounted on bracket 27 which in turn is carried by mounting plate 20, this element being omitted in Fig. 7 in the interests of clarity. Condition responsive element 26 may be composed of a set of capsules similar to 23, the interior thereof being connected to the instrument output or transmitted pressure, as will be described hereafter. As an alternative, if a valve is being positioned, a connection from the valve can be used in place of the element 26 shown.

The unitary algebraic comparing or differential mechanism is generally indicated at it (Fig. l), which serves to algebraically compare the movements of the condition responsive elements 23 and 26, the output of the algebraic comparing means being used to operate the flapper.

In order to obtain the desired accuracy and sensitivity, the construction herein permits the use of a motion multiplying means between the condition responsive means and the algebraic comparing mechanism. This is in contrast with many previous mechanisms wherein the motion is reduced. The condition responsive element 23 is connected to link 28 which in turn is connected to segment 29 (Fig. 1) through adjusting mechanism 30, segment 29 being mounted on shaft 31 between top plate 21 and bottom plate 22, with the end of shaft 31 located r 3 in aperture 32 of top plate 22. Part of link 28, mechaiiisrn 30, segment 29 and related parts are broken away and are omitted in Fig. 7 for clarity.

Output pressure responsive or followup condition remotion multiplying mechanism between the condition responsive means and the unitary differential or algebraic adding means 10.

The differential mechanism may comprise a carrier composed of bearing plate 35 and nozzle or flapper segment 46 integral with segment plate 46A, said plates being suitably spaced and carrying planetary gears 38, 39 (Figs. 2, 3), the planetary gears being engaged with each other at their inner ends and each gear being engaged at its outer end with its respective input pinion 40, ll. The shafts of the planetary gears are carried by plates 35 and 46A. The input pinions are rotatably mounted on the differential shaft 42, said shaft being journalled between top plate 21"and bottom plate 22. Input pinion 40 has an extension 46A to which hand 16 of air issuing from nozzle passage 49 and thus aifect the pressure therein. Condition responsive element 26 is connected to the relayroutput controlled by the air 7 pressure head of nozzle 43, such a relay being indicated in plate 21, pinion as carrying one end of shaft 42, the

other end of shaft 42 being journalle-d in plate 22. The flapper, baffle, or valve 43 is carried by flapper gear 44, which is engaged by segment 46, gear 44 being mounted on flapper arbor 45, said arborbeing suitably carried by top plate 21 and bottom plate 22. Hairsprings 15 can be connected to their respective input pinions in the usual manner. The particular construction and arrangement of the flapper and nozzle will be described at a later point, such being the subject of copending application Serial No. 413,319, filed November 1, 1954;

In the form shown, the motion of the algebraieconrparing assembly'is multipled although it is not entirely necessary that such multiplication be employed. It is to be noted that the flapper is connected directly to the differential output through a multiplying segment or otherwise. The nozzle shown generally at 48 (Fig. 2) is adjustably mounted on. top plate 21. The nozzle is connected to a source 'of supply air through a constriction in the usual manner. Nozzle passage 49 terminates at surface 5-2, which is angularly disposed relative to the longitudinal axis of the nozzle passage and valve surface 51 with which it cooperates. 51 of flapper -Sis angularly disposed with respect to the nozzle axis. The angle between the axis of the nozzle and the face thereof should be other than 90 in order to obtain optimum sensitivity for the reasons set forth in detail in said copending application Serial No. 413,319. By locating the surfaces at an angle relative to each other, among other advantages is a lessening of dead spots as tr e nozzle and flapper approachclosely to.

each other. In the example shown, the aforementioned angle is Cleaning mechanism 11 can be provided for cleaning the nozzle, such being operated by pushing the plunger inwardly. A spring (not shown) can return the cleanin plunger 11A to retracted position.

Describing the operation, upon a change of condition of the measured variable, responsive element 23 will be moved to operate link 28, link 28 causing rotation of segment 29, which in turn will rotate algebraic comparing means input gear At this particular moment, the follow-up input gear if will be stationary so that rotation of gear 46 will cause rotation of the planetary pinion assembly segment 46 therewith about the axis of shaft 42 by action of planetary pinions 38, 39. This will result in a movement of the flapper 43 relative to the nozzle 38 so as to increase or decrease the amount The valve surface by 12 in Fig. 7, pipe 13 being the connection. The relay or pilot output pressure is transmitted by pipe 14 to the condition responsive element 26. A change in the pressure in the nozzle will immediately result in movement of responsive element 26, which in turn will cause rotation of input gear 41 and thereby tend to cause flapper 43 to return toward its original position existent before the change of condition in 23, the flapper and nozzle reaching a new relative position. Thus, the differential mechanism 10 will algebraically compare movements of condition responsive elements 23. and 26, said movements being amplified. The input pinions, planetary pinions and related parts provide a construction which is statically and dynamically balanced such not being true of conventional complicated lever systems. if desired, the position of the differential can be brought to an indicator on the face of the instrument to show the amount oif balance (not shown).

In order to set the zero of the instrument, condition responsive element 25 can be mounted on post (Figs. 1, 4 omitted for clarity in Fig. 7) which is screwthreadedly carried by worm Wheel 61, wormwheel 61 being mounted in bracket 27 and resting on washer 61A.

Spring 62 urges the assembly upwards relative to bracket 27, said spring being in the form of a cross and being prevented from rotating on bracket 27 by suitable pins (not shown) or other means. Worm wheel 27 and is operable fromthe front of the instrument by slotted head 64 or from the rear by slotted head 65 for the purpose of adjusting the relative height of condition responsive element 26 upon bracket 27. Thus, the instrument can be readily set from the front.

It frequently is desirable to check with a master gauge the transmitted air pressure at the instrument. In order to accomplish this, valve socket or connector means (Figs. 1, 5) may be mounted on the mounting plate 20 of the instrument. Connector means 70 may have an aperture 71 in which is mounted an automatic closing valve 72. Said valve may be of the conventional tire valve type screwthreadedly engaged at 73 with connection 70 in said aperture 71. A suitable pipe con- 71. As valve knob '75 is movedinwardly, the inner end of the valve plug 77 will strike valve stem 81 of valve 72 and open the same so asto permit pressure from .74*to be exerted through. aperture 71 and-passagejsl ofithe valve body 73 to a suitable instrument]corn iected' topost 82 of the valve plug body.

If desired, the movement assembly can be assembled in a compact casing, together with its pilot as indicated in Fig. 7. The relay base may be an integral part of the back casting or plate 17 of the assembly. For-- example,

the length may be as low as in the range of 4 /2 inches and thehcight as low as in the range of 4% inches. The relay or pilot 12 thereof is the subject matter of copending application Serial No. 404,906, filed January 19, 1954.

In Fig. 6 may be seen a front view of the movement assembly, the adjustment point 64 and testing connector 70 being seen at the front of the face.

Referring to Fig. 7, the critical case 85 can be removed from the back plate 86 and thus expose all functional components for'calibration and test. 3

It is to be understood that the instrument'or the move- Worm gear 63 engages;

ment assembly can be used for various purposes and that the principles of the invention can be applied to indicators, recorders, transmitters and controllers including proportional band controllers. Details of construction and arrangement can be varied without departing from the spirit of the invention as defined in the appended claims.

What is claimed is:

1. In a condition responsive means for producing an output pressure in response to a measured variable, the combination comprising two condition responsive means, unitary algebraic comparing means connected to the output of said condition responsive means, said comparing means having input pinions and planetary gear means engaging said input pinions, the planetary gear means moving according to movement of said input pinious relative to each other and producing an algebraic output movement, one of said condition responsive means being responsive to a measured variable and being connected to one of said input pinions, pressure control means directly connected to the output of said algebraic comparing means, means connecting the pressure controlled by said pressure control means with the other of said condition responsive means, and means connecting the other of said condition responsive means with the other of said input pinions.

2. In a condition responsive means for producing an output pressure in response to a measured variable, the combination comprising two condition responsive means, unitary algebraic comparing means connected to the output of said condition responsive means, said comparing means having input pinions and planetary gear means on offset shafts relative to said input pinions, said gear means engaging said input pinions, the planetary gear means moving according to movement of said input pinions and producing an algebraic output movement, one of said condition responsive means being responsive to a measured variable and being connected to one of said input pinions, nozzle and flapper pressure controlling means directly connected to the output of said algebraic comparing means through motion multiplying means, means connecting the pressure controlled by said pressure control means with the other of said condition responsive means, and means connecting the other of said condition responsive means with the other of said input pinions.

3. In a condition responsive means for producing an output pressure in response to a mea ured variable, the combination comprising two condition responsive means, unitary algebraic comparing means connected to the output of said condition responsive means, said comparing means including shaft means carrying a pair of input pinions, said input pinions being engaged with a pair of planetary gears mounted on ofi'set shafts parallel to said shaft means, a carrier for said planetary gears and having an output movement arm, one of said condition responsive means being responsive to a measured variable and having motion multiplying arm means connecting the same with one of said input pinions, means connecting said input pinion with an indicator means, a flapper valve directly connected to the output of said algebraic comparing means, said valve cooperating with a nozzle to control air pressure therein, means connecting said air pressure controlled by said flapper valve with a second of said condition responsive means, and motion multiplying arm means connecting the second condition responsive means with the other input pinion.

4. In a condition responsive means for producing an output pressure in response to a measured variable, the combination comprising two condition responsive means, unitary algebraic comparing means connected to the output of said condition responsive means, said comparing means including shaft means carrying a pair of input pinions, said input pinions being engaged with a pair of planetary gears having an output movement arm, said planetary gears being mounted on shafts ofiset relative to said shaft means and substantially parallel thereto, one of said condition responsive means being responsive to a measured variable and having motion multiplying arm means connecting the same with one of said input pinions, means connecting said input pinion with an indicator means, a flapper valve directly connected to the output arm of said algebraic comparing means through motion multiplying means, said valve cooperating with a nozzle to control air pressure therein, relay means responsive to the air pressure controlled by said nozzle, means connecting the output of said relay means With the second condition responsive means, and motion multiplying arm means connecting the second condition responsive means with the other input pinion.

5. In a condition responsive means for producing an output pressure in response to a measured variable, the combination comprising a compact case having a back plate, support means mounted in spaced relation to said back plate, two condition responsive means mounted on said support means, statically and dynamically balanced unitary algebraic comparing means mounted on said support means connected to the output of said condition responsive means through arm and segment motion multiplying means, one of said condition responsive meansbeing responsive to a measured variable, flapper and nozzle pressure means movable relative to each other by the output diflerential movement of said algebraic comparing means, pressure relay means mounted on the back plate of said case and connected to the pressure controlled by said flapper and nozzle means, means connecting the pressure controlled by said pressure relay means with the other of said condition responsive means, and indicator means connected with the movement of the first of said condition responsive means to give a reading of the measured variable.

6. In a condition responsive means for producing an output pressure in response to a measured variable, the combination comprising a frame means having a front face, two condition responsive means mounted on said frame, the first of which is responsive to the measured variable, statically and dynamically balanced differential gear unitary algebraic comparing means connected to the output of said condition responsive means, pressure control means connected to the output of said algebraic comparing means, means connecting the pressure controlled by said pressure control means with the second of said condition responsive means, mounting bracket means on said frame means for carrying said second condition responsive means, worm and Wheel means between said bracket means and said condition responsive means, and means for turning said Worm and Wheel means relative to each other for adjusting the position of said second condition responsive means relative to said bracket.

References Cited in the file of this patent UNITED STATES PATENTS 1,959,786 Hodgkinson May 22, 1934 2,061,118 Vogt Nov. 17, 1936 2,212,085 Tate Aug. 20, 1940 2,213,446 McGrath Sept. 3, 1940 2,276,505 Moore Mar. 17, 1942 2,326,238 Mabey Aug. 10, 1943 2,361,885 Tate et al. Oct. 31, 1944 2,381,948 Sess Aug. 14, 1945 2,507,606 McLeod May 16, 1950 2,518,674 Fischer et al. Aug. 15, 1950 2,529,875 Howard Nov. 14, 1950 2,593,129 Fischer Apr. 15, 1952 2,618,978 Ragland Nov. 25, 1952 2,632,456 Breedlove t Mar. 24, 1953 FOREIGN PATENTS 225,474 Great Britain Dec. 4, 1924 

